add a custom screen in minecraft launcher jar file

Choose a name for the instance, set a group for it (You can make a group by typing it in the box), you can select an icon for it (You can also add custom icons from the icon dialogue).

Without a default selection, MultiMC will ask you which account you wish to use on every launch. You can set a default account by clicking Set default. Click Add Microsoft or Add Mojang and follow the prompts.Start by clicking on the face in the top right corner and then Manage Accounts.MultiMC sends anonymous statistics every time the application starts.This is done for the further development of MultiMC and also to know which platform to focus on more.

If you installed Java elsewhere then click the browse button and browse to the installation.If your version of Java does not show up, please file an issue.You should use a 64bit Java if you are on a 64bit OS.Then you will be prompted for which version of java to use. Once launched, you will be prompted for which language to use for running MultiMC Linux: Double click MultiMC (in the root where you extracted, not bin/MultiMC).Once downloaded, extract the archive to your desired place.

Add a custom screen in minecraft launcher jar file